A workpiece holder comparable to an embroidery frame, which can be detachably fastened by means of a device to a drive member of a sewing machine that can be moved in parallel to a support surface for the workpiece holder, has been known from DE 42 08 726 A1. The fastening device contains a pair of pins, which are provided with a head and are arranged either on the workpiece holder or on the drive member, and a pair of engaging grooves, which can be engaged with the pins and are formed on the other of the two parts. The pins and the grooves form coupling means acting in a positive-locking manner, wherein the workpiece holder is coupled on and off by a movement directed at right angles to the support surface. A cam-shaped finger, which is fastened to the workpiece holder or to the drive member and cooperates with a leaf spring of a corresponding shape arranged on the respective other part, is used for the nonpositive locking of the coupled workpiece holder. Since the workpiece holder is guided freely by hand during the coupling and uncoupling, which takes place in the vertical direction, it may easily happen that it assumes an oblique position and that the pins will be jammed in the engaging grooves as a consequence of this.
This risk is avoided in the fastening device for an embroidery frame known from DE 32 01 014 C1 by the embroidery frame always lying on the support surface of the machine during the coupling and uncoupling. The fastening device comprises a T-shaped holding element, which is arranged on the outside of the embroidery frame and can be fastened to the drive member of the machine by means of a fixed stop and a movable stop in the manner of a spring-loaded detent pawl. To make it possible to correctly engage and disengage the T-shaped holding element with the drive-side coupling elements, which are in a hidden location, during coupling and uncoupling, the operator must, however, perform a combined pushing and pivoting movement with the embroidery frame, which always requires a comparatively great skill to be properly successful.